Putting a 486 desktop online

I recently acquired an old 486 desktop, an AST Bravo LC 4/25s. It runs MS-DOS 6.22, and obviously lacks any sort of networking out of the box. After wondering what I would do with it, I decided to try to put it on the internet. It turns out that it is actually possible to put these old computers on a modern TCP/IP network even in 2018. By using an ISA network card and the mTCP network stack, you can go online and browse some websites on your DOS rigs.

The network card I chose for this project is a 3Com EtherLink III. It supports a maximum speed of 10 mbps, so it is quite slow, but not exactly slow for the time period. These cards can be found on eBay for around $10. Make sure it’s ISA and you’ll be good. The drivers for this card are no longer available on 3Com’s website, but they can be found here. The file you’ll want is 3C5X9X.EXE.

Installing the network card

Driver installation is simple; run 3C5X9X.EXE and then install the packet driver to C:/DOS. You’ll then want to edit your autoexec.bat to tell DOS to load the driver. Appending the following snippet will load the driver when you boot DOS:

loadhigh c:\dos\3c5x9pd.com 0x60

0x60 is the interrupt my card runs on; yours will likely be the same. If it is not, the driver installer should tell you what interrupt it is on.

Setting up mTCP

Next up is setting up mTCP. mTCP is a modern network stack for MS-DOS and FreeDOS. It was last updated in 2015, and it contains multiple utilities like an IRC, DHCP, NTP, and Telnet client. In order to install mTCP, download the latest version here. I extracted the files to C:\APPS\MTCP, but you can install it wherever you want.

First up, you’ll want to make a configuration file. Save it to C:\APPS\MTCP\MTCP.CFG

packetint 0x60
hostname 486Box

Next, edit autoexec.bat, and add the following lines:

set MTCPCFG=c:\apps\mtcp\mtcp.cfg
c:\apps\mtcp\dhcp.exe

When done, reboot. Assuming you’re using DHCP like in the example, you’ll be given an IP.

Going online

While you can’t do much with a DOS machine on the internet anymore, you can still use it to do some tasks. There is a web browser for DOS called Arachne that supports most of HTML3 and supports loading images. It isn’t fast, though. On my 486, some web pages take upwards of 5 minutes to fully load, if they do at all.

If you’d rather do some practical work, mTCP’s telnet client works quite well. I found that it is quite possible to use this 486 desktop to do linux administration tasks. However, if you do decide to run a telnet server for this, keep it LAN only because telnet is unencrypted!